SAN FRANCISCO, CA—Ustekinumab (UST) benefits psoriatic arthritis (PsA) patients with spondylitis and peripheral joint involvement, according to a subgroup analysis of results from the PSUMMIT 1 & 2 Phase 3 double-blind, placebo-controlled clinical trials. The authors reported their findings at the 2015 ACR/ARHP Annual Meeting.
“In this post-hoc subgroup analysis of patients with spondylitis and peripheral joint involvement at baseline, UST-treated patients demonstrated significantly improvement in axial related signs and symptoms, enthesitis and dactylitis, physical function, and reduction in radiographic progression versus placebo through Week 24,” reported lead study author Arthur Kavanaugh, of the University of California San Diego in La Jolla, California, and coauthors.
“UST was well-tolerated in this subset of PsA patients, with safety findings similar to the overall population,” Dr. Kavanaugh noted.
Ustekinumab is a fully human monoclonal antibody that binds to IL12 and IL-23; the PSUMMIT 1 & 2 trials showed it to be safe and effective against active PsA. “Recent research suggests that IL-23 pathway is involved in pathophysiology of axial disease and open-label study data suggests that UST may be effective in ankylosing spondylitis (AS),” noted Dr. Kavanaugh.
The post-hoc analysis was based on data from adult PsA-diagnosed patients with active disease, who had been randomly assigned to receive UST 45mg, 90 mg, or placebo at Weeks, 0 (baseline) and 4, and then every 12 weeks. Patients in the placebo group crossed over to the UST 45mg group at Weeks 24 and 28, and then received UST every 12 weeks, the authors noted.
“At Week 16, patients with less than 5% improvement in TJC [tender joint counts] & SJC [swollen joint counts] entered blinded early escape [EE],” the coauthors noted in a poster presentation. “BASDAI scores were collected at baseline and weeks 12 and 24; BASDAI question (#2), related to overall level of axial disease neck, back or hip pain, was also assessed separately.”
A total of 256 patients with spondyloarthritis at baseline, representing 28% of PSUMMIT 1 &2 participants, who had been randomly assigned to receive UST (n=164) or placebo (n=92) and a total of 32 of whom were biologics-experienced.
“In the spondyloarthropathy (SpA) subgroup, 80.5% of patients had enthesitis and 51.6% had dactylitis at baseline,” Dr. Kavanaugh said. “Consistent with the overall population, at baseline, about 50% of patients used methotrexate, 77% used NSAIDs, and 21% used oral corticosteroids with a median dose of 6mg/day.”
Patients treated with UST combined more frequently achieved BASDAI-20/50/70 responses than patients receiving placebo at Week 24 (164 patients [54.8%/29.3%/15.3%] vs. 92 patients [33%/11.4%/0]).
The observed changes in the median score of BASDAI question #2, which is related to the overall level of axial disease neck, back or hip pain, were -1.65 for the combined-UST group, vs. -0.45 for placebo, similar to the median changes noted in the total BASDAI score, he noted.
Adverse event (AE) rates for placebo vs. combined UST-treated groups were 41.3% vs. 34.8%; serious adverse events (SAEs) occurred in 2.2% vs. 1.2%, respectively, and treatment discontinuations due to AEs were recorded in 3.3% vs. 0.6% of patients, they reported. Infection rates were similar between the placebo and UST groups (16.3% vs. 13.4%, respectively).
“Throughout Week 16, the proportion of patients with adverse events was comparable in placebo vs. combined UST-treated group,” Dr. Kavanaugh noted.